Liquid refrigerator



1942- R. H. HUBBELL LIQUID REFRIGERATOR 3 Shee ts-Sheet 1 Filed Aug. 3,1940 V 2 i i A .m 1

ATTORNEYS.

NOV. 10, 1942. I R H, HUBBELL 2,301,546

LIQUID REFRIGERATOR Filed Aug. 3, 1940 3 Sheets-5heet 2 INVENTOR.

/feed Wzz/kzZ ATTORNEYS.

Nov. 10, 1942. R. H. HUBBELL 2,301,546

LIQUID REFRIGERATOR Filed Aug. 3, 1940 3 Sheets-Sheet 3 INVENTOR.

ATTORNEYS Patented Nov. 10, 1 942 UNITED STATES PATENT OFFICE 12 Claims.

My invention relates to liquid refrigerators, and niore especially toliquid refrigerators of the type where the liquid to be cooled runs overthe surface of a hollow (double-walled) evaporator of a refrigeratingsystem.

My liquid refrigerator is disclosed herein as applied specifically tocooling the water for a carbonator, but I contemplate that it may coolwater for other purposes and that it may cool other liquids than water,such as for example milk.

Among the objects of my invention are the following: A refrigeratorwhich has a large cool-- ing capacity in proportion to the area of thesurface over which the water runs; uniformity of heat absorption overthe surface; a large cooling capacity in proportion to floor areaoccupied and without such height as to interfere with the installationof a unit in which the refrigerator is incorporated, beneath ordinaryceiling height; ease of cleaning; and general simplicity and economy.

Further objects, features and advantages of my invention are set forthin the following description of specific embodiments thereof andillustrated in the accompanying drawings, wherein:

Fig. 1 is a vertical section of a device embodying my invention;

Fig. 2 is a top plan view of the device showing certain associatedstructure in section;

Fig. 3 is a plan section taken on the line 3-3 of Fig. 1; and

Fig. 4 is a diagram of the refrigerator and its refrigerating system anda carbonator feeding therefrom.

Referring to Fig. 1, my liquid cooling evaporator I is in the form of adouble-walled tubular shell. It consists of an outer tube II and aninner tube I2. At its upper end, the outer tube I I is swaged or spuninwardly and, at its upper end, the inner tube I2 is swaged or spunoutwardly. The ends of the two tubes thus have mating cylindricalsurfaces at their upper ends which are in surface contact and are weldedtogether in fluid-tight connection at I3. The double thickness upper endof the evaporator II is centered halfway between the bodies of the tubesII and I2, giving, in radial section, a symmetrical form.

The inner and outer tubes are joined together at their'bottom ends at Itin a similar manner, except that for manufacturing economy all of theswaging or spinning is done on the inner tube I2. The refrigerant, whichmay be Freeon, is fed into the annular hollow space I5 between the tubesII and I2 adjacent their bottom by an inlet pipe I6 welded to the outertube, and is led an outlet pipe I! welded to the outer tube near itsupper end. a

If the annular refrigerant space I5 were entirely open and unobstructed,there would be a g tendency for the refrigera forced in through theinlet pipe I6 to follow the shortest path to the outlet pipe I'I,leaving relatively stagnant regions. To avoid this, I annularly restrictthe bottom of the space I5, just above the inlet pipe I6, by a ring II.This may be a rod formed into an annulus, the rod being of a diameterconsiderably less than the spacing of the outer and inner tubes II andI2. The constriction afforded by the rod I8 causes the pressuretherebelow to be enough greater than the pressure thereabove to insure afairly uniform distribution of the upflow of refrigerant past the rod I8at all arcuate regions.

Uniform distribution of the flow of refrigerant through the space I5 isfurther implemented by a set of arcuately spaced partitioning strips i9disposed between the inner and outer tubes. These can be arranged asparallel spirals if it is desired to retard the vertical speed of flowof the refrigerant through the space I5. In the form illustrated,because I prefer not to retard the flow, the strips I9 are arrangedvertically. They may be welded, as at 20, to the exterior of the innertube I2 before the inner tube is inserted into the outer tube and weldedthereto. The fact that the lower end of the outer tube I I i not swagedor spun inwardly permits the inner tub II, with the strips I9 welded orbrazed thereto, to be inserted through the lower end of the outer tubeII. Thus, the top and bottomswaging of the tubes may be done before theyare assembled.

The partitioning strips I9 extend from the ring I8 to the height of theunderside of the outlet pipe II.

A feed trough 2i sets on the upper end of the evaporator Ill. The feedtrough 2| is in the form of a cup having outer and inner concentriccircular rows of holes 22 and 23 in its bottom. The circle of holes 23are arranged on such a diameter that they come just inwardly of the topedge of the evaporator while the outer holes 22 come just outwardlythereof. The cup may be centered by positioning ears 24 depending fromthe bottom of the cup and fitting against the inner margin of the top ofthe evaporator.

A tubular feed well 25 rises centrally from the bottom of the feedtrough. Water to be cooled 7 drops from-a centrally positioned feed pip26 into the well 25, and overflows the well into the from the hollowspace ii of the evaporator by annular trough which surrounds the well.In this tube I2. That passing through the holes 22 passes down over theouter surface of the outer tube II. The swaging or spinning of the innerand outer tubes adjacent their upper margins forms rounded shouldersimmediately beneath the respective rows of holes 23 and 22, so that thewater passing through the holes cannot fall clear of the surfaces of thetubes. These rounded shoulders also tend somewhat toequalize-annularly-the flow of water over the tubes.

The evaporator It! may conveniently be from five to ten inches indiameter and some five feet high. The water flowing down over thesurfaces of the evaporator clings to the metal walls as a film, ratherthan falling free thereof, despite the speed which the water achieves bythe time it reaches the bottom of the evaporator. When the water passesoff the bottom of the evaporator, it falls into an insulated receiver21. Splashing of the waterdropping from the bottom of the evaporator maybe eliminated by an extension tube 28 in the form of a split cylinderremovably surrounding the bottom of the evaporator and extending downsubstantially to the bottom of the receiver 21. The water will thenfollow the surfaces of the extension tube.

Referring now to the rather diagrammatic circuit of Fig. 4, the watesupply pipe 29 leads through a pressure regulator 30, to assure a cornstant pressure for the water passing through the adjustable feed valve3|. Thence through a solenoid cutofi valve 32, the water continues tothe feed pipe 26. From the receiver 21, water is removed from time totime and taken in through a pipe 33 to a carbonator 34 through anelectrical circuit, not shown but well known. A liquid contact switch 35controls the opening and closing of the solenoid valve 32. When theliquid level reaches the upper contact of the switch 35, the feed valve32 is closed; when it drops down below the lower electrode, the feedvalve 32 is opened. Thus, an adequate supply of cold water is maintainedat the receiver 21 to meet the intermittent requirements of thecarbonator 36, but the water cooler operates intermittently. Thevertical space between the upper and lower contacts of the switch 35represents a large enough volume of water so that the intermittentoperation of the cooler will not involve frequent operations of thecooler for short periods.

Still referring to Fig. 4, I shall now describe the refrigerant cycle.The outlet or suction pipe I! for the evaporator Ill leads tangentially(see Fig. 2) into a drum-shaped accumulator 36. This gives the returns aswirling motion to aid, by centrifugal force, the separation of therefrigerant gas from the still liquid refrigerant. The refrigerant gasis sucked out of the accumulator 36 through a depending tubular exhaustport 3'! (Fig. 1), the baflling out of the liquid being improved by anannular horizontal flange :38 near the bottom of the tubular port.

From the exhaust port 31, the gas passes through a suction line 39,which in turn goes through a heat interchanger 40, and through a backpressure regulator M to the suction side of a compressor 42. From thepressure side of the compressor, the refrigerant goes through acondenser 43 to a liquid refrigerant receiver 46.

From the receiver 44, the liquid refrigerant passes through a pressureline 45, the heat interchanger All, and through an injector nozzle 46into the inlet pipe IS.

A down pipe 41 also leads to the inlet pipe It by way of the injectornozzle 46. By means of the injector nozzle, liquid refrigerant left inthe accumulator 36 is caused-despite its low pressure-to recirculatethrough the evaporator. In fact, I prefer that by and large the greaterportion of gas returned through the outlet pipe ll be still in liquidform and recirculated without going back through the compressor. In thisway. the space l5 in the evaporator is more nearly completely filled byliquid refrigerant which offers much greater heat absorption thanrefrigerant gas. Thereby the capacity of the evaporator is kept muchhigher in proportion to its surface over which the water travels.

The circuit of the motor 48 may be in parallel with the circuit of thesolenoid water feed valve 32 so that, when the water in the receiverreaches its upper lever, and the solenoid circuit is broken to allow thefeed valve to close, the circuit of the motor 48 is also closed. And,conversely, when the liquid in the receiver reaches its lower level andthe circuit of the solenoid valve is closed to open the valve, the motorcircuit is closed to operate the compressor.

As shown in Figs. 1 and 2, the evaporator is partitioned from theaccumulator 36 by a vertical wall 49, through which the inlet and outletpipes i6 and I! pass, A semicircular removably mounted rear shell 50 mayenclose the back side of the wall 49, the accumulator 36, heatinterchanger 40, and incidental fittings. The evaporator and feed troughmay be enclosed by a. front semi-cylindrical shell 5i detachably mountedto the front side of the wall byclamps 52. At its bottom, the frontshell 5i may carry, or rest upon, a horizontal apron 53 which covers thetop of the receiver 21. This aids sanitation by keeping dust and dirtout of the water being cooled. When the shell and apron are removed forcleaning the trough, evaporator and receiver, the wall 49 forms areadily clean partition which keeps any dirt from the more difiicultlycleaned parts on the back side of the wall getting on to the evaporatoror into the receiver.

The inner and outer tubes H and i2 of my evaporator may be made ofstainless steel, but in the interest of greater conductivity, I preferto make them from copper tubes with their eX- posed surfaces chromiumplated to prevent corrosion but dull finished to facilitate heattransfer. The exposed surfaces of the evaporator present a minimum ofhard-to-clean pockets, ridges or the like, such as are often encounteredin corrugated coolers. The interior of the evaporator, being of a fewinches in diameter, is large enough to permit its being cleaned,although a hot liquid wash will ordinarily suffice without the use of abrush. The feed trough 2| merely rests upon the upper edge of theevaporator but is unattached to the evaporator or to the feed pipe 26 sothat the trough 2! may readily be taken out for easy cleaning. Becausethe refrigerant is fed into the bottom and travels upwardly, it iscoldest near the bottom where the water, which becomes colder as itpasses downwardly. encounters the coldest refrigerant at the end of itstravel. This makes possible the maximum reduction of the watertemperature in proportion to the temperature of the refrigerant as it isfed into the evaporator.

If the tubes Ii and if of myevaporator were annularly corrugated, theywould tend to throw oi! the fast moving water, especially toward thelower end of the evaporator when the water is during those phases. Byproviding my evaporator with smooth cylindrical vertical surfaces,

l preserve a uniform pressure of contact of the water with the surfacesthroughout the length of the evaporator. This pressure of contact, itwill be understood, comes from the attraction of the water to thesurfaces causing the down traveling water to film thereupon. Becauseof',the skin friction of the water, there is a continual eddying of thewater providing a circulation as between the outer and inner layers ofthe water film, and this further accelerates the ab? sorption of heat bythe evaporator of all of the water passing over it.

Because of the advisability of keeping the height of the evaporatorwithin limits in the order of five feet so that the cooler unit can beinstalled -beneath any ordinary sealing height, and also to avoid thedimculty of holding a thick water film on the surface of the evaporatorwhen it has gained too much speed, I prefer, in enlarging the capacityof my cooler, not to do so by making it longer but rather by making itof greater diameter to provide more surface. When the capacity requiredwould involve an excessive diameter, a battery of evaporators may beemployed, arranged side-by-side, in one cooler unit with the refrigerantinlet and outlet pipes and the water feed pipe appropriately manifolded.it will be seen that my evaporator is peculiarly susceptible of suchbattery installation in a single unit.

The water, constantly gaining speed from gravity, although held backsomewhat by the attraction of the metal surface of the evaporator andskin friction therewith, will be moving very much faster toward thebottom of the evaporator than toward the top. Consequently, thethickness of the water film on the evaporator surfaces will beconsiderably thicker at the top than at the bottom, It is desirable tohave the water film thinner'as it approaches the bottom of theevaporator, partly to offset the increased speed increases as the"refrigerant weight-velocity" increases. By this I mean that heattransfer is increased with an increase in the weight of the refrigerantpassing over the heat transfer surface and the velocity with which ittravels over the surface. One of the virtues of my liquid coolingevaporator is that it achieves a high degree of refrigerantweight-velocity. The refrigerant passage through the evaporator is astraight streamlined passage free from those turns and pockets which areapt to foster oil pockets, gas pockets, retarding eddies, stagnantregions, and general sluggishness in the refrigerant flow. Throughoutsubstantially all of the height of the refrigerant passage through theevaporator, the wallsare equally spaced and the cross-sectional area ofthe annular space is constant at all heights. This preserves anuniformity of the high velocity with little pressure drop. Thecross-sectional annular area of the passage is small enough, in relationto refrigerant fed, to induce a high velocity.

The high velocity fosters greater heat absorptioif because it brings theliquid refrigerant into more of a scouring contact with the transferwall. The high velocity also carries off accumulating gas bubbles fromevaporation more rapidly so that a higher percentage of the refrigerantmay remain in liquid form, a liquid in contact with the transfer surfaceabsorbing heat very 'much' more rapidly than gas in contact with it. v

The elimination of a float valve with its flowretarding effect and theuse of the surge drum or accumulator permits a high percentage'of therefrigerant removed from the evaporator to be removed in the form of aliquid and recirculated along with liquid coming from the condenser.This permits the refrigerant in the evaporator to be maintained muchmore solidly" as liquid.

When I mention the advantages of the inner and outer tubes of myevaporator being cylindrical and uncorrugated, I am referring to theabsence of horizontal corrugations. The cylindrical tubes might beconcentrically ovalized, although that would be more expensive tomanufacture; and they, might be similarly fluted or corrugatedvertically to increase the surface without increasing the heights,although I prewith the attendant lessened time interval of :ontact ofthe water film with each vertical inch of surface and partly to increasethe final transfer of heat. The thinner the film, the more effective isthe absorption of heat from all of the water in the film because thereis not so much water in outer layers insulated by the inner layer ofwater in the film.

The elimination of a header on the top of the evaporator eliminates theproblem of carrying the water around the header before it is fed on tothe heat transfer surfaces of the evaporator. This and the water feedtrough combine to pro- :luce a high degree of uniform distribution ofthe water upon the cooling surfaces. The distribu- :ion is also ratherevenly balanced as between :he inner surface and the outersurface of theannular evaporator throughout wide variations if water feed.

The heat transfer capacity of an evaporator fer, rather than incurringthat expense, to increase the diameter of the evaporator or to use abattery of evaporators.

My evaporator is very easy to clean, has a high capacity in proportionto its size, and its crosssectional area is very small and compactlyarranged so that in designing the other parts of the cooling unit inwhich the evaporator will be incorporated, the evaporator. itselfbecomes a very minor factor in the floor space which the evaporator mustoccupy and therefore, in general, a liquid refrigerating unit employingmy evaporator may be designed more compactly and occupy less floorspace,

Having thus described my invention, what I claim is:

1. A liquid cooler comprising concentrically and vertically disposedinner and outer metal tubes having straight vertical walls and sealedtogether at top and bottom to form a headerless evaporator with anannular refrigerant space between the tubes substantially co-extensivelywith the tubes. means for feeding liquefied vaporizing refrigerant intothe bottom of the refrigerant space and for exhausting refrigerant fromthe top, means at the top of the tubes for feeding a liquid to be cooledon to the outer surface of the outer tube and inner surface of the innertube to run downwardly under gravity as a film over the surfaces, andmeans within the refrigerant space for substantially uni ormly distributing the upflowing refrigerant through such space.

2. A liquid cooler comprising concentrically and vertically disposedinner and outer metal tubes having straight vertical walls and sealedtogether at top and bottom to form a headerless evaporator with arefrigerant space between the tubes substantially co-extensively withthe tubes, means for feeding liquefied vaporizing refrigerant into thebottom of the refrigerant space and for exhausting refrigerant from thetop, means at the top of the tubes for feeding a liquid to be cooled onto the outer surface of the outertube and the inner surface of the innertube to run downwardly under gravity as a film over the surfaces, theupper margin of the outer tube being annularly ensmalled and the uppermargin of the inner tube being annularly enlarged to bring the tubesinto sealing contact at the upper end, and partitions fixed upon theinner tube to lie within the refrigerant space between the tubes, thelower margin of the inner tube being annularly enlarged beyond thecircumscribing diameter of the partitions into sealing contact with theouter tube.

3. A liquid cooler comprising concentrically and vertically disposedinner and outer metal tubes having straight vertical walls and sealedtogether at top and bottom to form a headerless evaporator with a,refrigerant passage between the tubes substantially co-extensively withthe tubes, means for feeding liquefied vaporizing refrigerant into thebottom of the passage and for exhausting refrigerant fro-m the top,means at the top of the tubes for feeding a liquid to be cooled on tothe outer surface of the outer tube and the inner surface of the innertube to run downwardly under gravity as a film over the surfaces, andarcuaiely and paralleily spaced stnps extending upwardly through thepassage to partition the passage into parallel subpassages, for thepurpose described.

4. A liquid cooler comprising concentrically and vertically disposedinner and outer metal tubes having straight vertical walls and sealedtogether at top and bottom to form a headerless evaporator with arefrigerant passage between the tubes substantially co-extensively withthe tubes, means for feeding liquefied vaporizing refrigerant into thebottom of the passage and for exhausting refrigerant from the top, meansat the top of the tubes for feeding a liquid to be cooled on to theouter surface of the outer tube and the inner surface of the inner tubeto run downwardly under gravity as a film over the surfaces, arcuatelyand parailelly spaced strips extending upwardly through the passage topartition it into subpassages, and a ring interposed between the tubesabove the refrigerant feeding means but below the strips, for thepurpose described.

5. A liquid cooler comprising concentrically and 'vertically disposedinner and outer metal tubes having straight vertical walls and sealedtogether at top and bottom to form a headerless evaporator with anannular refrigerant space between the tubes substantially co-extensivelywith the tubes, means for feeding liquefied vaporizing refrigerant intothe bottom of the refrigerant top, means at the top of the tubes forfeeding a liquid to be cooled on to the outer surface of the outer tubeand the inner surface of the inner tube to run downwardly under gravityas a film over the surfaces, a receiver located beneath the evaporator,and an extension sleeve substantially aligned annularly with theevaporator and extending downwardly from the lower end thereof into thereceiver to receive and guide the films of water when they leave thesurfaces of the evaporator.

6. A liquid cooler comprising concentrically and vertically disposedinner and outer metal tubes having straight vertical walls and sealedtogether at top and bottom to form a headerless evaporator with arefrigerant space between the tubes substantially co-extensively withthe tubes, means for feeding liquefied vaporizing refrigerant into thebottom of the refrigerant space and for exhausting refrigerant from thetop, and means at the top of the tubes for feeding a liquid to be cooledon to the outer surface of the outer tube and the inner surface of theinner tube to run downwardly under gravity as a film over the surfaces,said refrigerant feeding and exhausting means including an accumulatorplaced within th height of the evaporator for receiving and separatingrefrigerant liquid and gas from the upper end of the evaporator and alsoincluding a passage for recirculating the liquid refrigerant from theaccumulator into the bottom of the evaporator.

7. A liquid cooler comprising, in combination, a headerless coolingdevice including inner and outer vertically extending and substantiallycoextensive tubular metal wall members sealed togather at the top andbottom of the device and spaced apart throughout their major extent todefine a vertical passage for a heat abstracting medium, means forintroducing a heat abstracting medium into the bottom portion of thevertical passage and for exhausting said medium from the top portion ofthe passage, means at the top of the cooling device for feeding a liquidto be cooled as substantially completely covering downwardly flowingfilms on to those respective surfaces of said wall members which areexterior to said passage, and means constructed and arranged within saidpassage for uniformly distributing the heat abstracting medium forupward flow therein to sweep the passage surfaces of the wall members.

8. A liquid cooler according to claim 7, wherein the distributing meanscomprises structure effective adjacent to the medium introducing meansat the bottom portion of the passage to restrict and uniformlydistribute the heat abstracting medium for upward flow.

9. A liquid cooler according to claim 7, wherein the distributing meanscomprises structure effective to equalize upward flow of the heatabstracting medium from the medium introducing means throughout thepassage, and also structure which divides the passage into separatedvertical subpassages for preventing deflection of the upflowing mediumfrom the distributed condition before the medium has risen high enoughin the passage to be exhausted.

10. A liquid cooler as set forth in claim 7, in which the distributingmeans is carried by one of said tubular wall members, and the membersare constructed and arranged to be assembled by a relative longitudinalassembly movement.

space and for exhausting refrigerant from the 11. A liquid coolercomprising, in combination, a device for cooling liquid by externalcontact with the liquid flowing vertically as a film thereover andincluding a pair of vertical metal tubes of substantially difierentdiameters and arranged one substantially co-extensive within the otherto provide a flow passage therebetween for heat abstracting medium, andmeans on one of said tubes constructed and arranged to distribute theheat abstracting medium in uniform flow through said passage, said tubeshaving opposite end portions joined together in abutment and sealed,with the end portion of the tube carrying said distributing meansdeformed to accommodate the distributing means and the remaining tubehaving its complementary and straight so as to receive the tube carryingthe distributing means with a relative longitudinal movement in theassembly of the tubes, said deformed end abutting said straight end andbeing sealed thereto.

12. In combination, in a liquid cooler, substantially co-extensiveupright heat transfer walls spaced apart throughout their major areas todefine a vertical flow passage of substantial height and of across-section narrow in one horizontal direction but of substantiallygreater extent in the transverse horizontal direction, the interior ofsaid passage being arranged for vertical flow of heat abstracting mediumfrom the bottom toward the top thereof, means for feeding the liquid tobe cooled in downward flowing films substantially covering therespective surfaces of said walls exterior to said passage, and meansconstructed and arranged to substantially uniformly distribute the heatabstracting medium for upward flow within the passage.

REED H. HUBBELL.

